which I find jotted down in the notes of this year to be written as an introduction to “Zoology,” together with the “Dog” as an introduction to the “Mammalia”, and “Man”—­already dealt with in “Man’s Place in Nature”—­as an introduction to “Anthropology.”  This projected series is completed with a half-erased note of an introduction to “Psychology,” which perhaps found some expression in parts of the “Hume,” also written this year.

He notes down also, work on the Ascidians, and on the morphology of the Mollusca and Cephalopods brought back by the “Challenger,” in connection with which he now began the monograph on the rare creature Spirula, a remarkable piece of work, being based upon the dissections of a single specimen, but destined never to be completed by his hand, though his drawings were actually engraved, and nothing remained but to put a few finishing touches and to write detailed descriptions of the plates.

Letters to W.K.  Parker and Professor Haeckel touch on this part of his work; the former, indeed, offering a close parallel to a story, obviously of the same period, which the younger Parker tells in his reminiscences, to illustrate the way in which he would be utterly engrossed in a subject for the time being.  Jeffery Parker, while demonstrator of biology, came to him with a question about the brain of the codfish at a time when he was deep in the investigation of some invertebrate group.] “Codfish?” [he replied,] “that’s a vertebrate, isn’t it?  Ask me a fortnight hence, and I’ll consider it.”

4 Marlborough Place, September 25, 1878.

My dear Parker,

As far as I recollect Ammocoetes is a vertebrated animal—­and I ignore it.

The paper you refer to was written by my best friend—­a carefulish kind of man—­and I am as sure that he saw what he says he saw, as if I had seen it myself.

But what the fact may mean and whether it is temporary or permanent—­is thy servant a dog that he should worry himself about other things with backbones?  Not if I know it.

Churchill has got over a whole batch of the American edition of the Vertebrata, so I have a respite.  Mollusks are far more interesting—­bugs sweeter—­while the dinner crayfish hath no parallel for intense and absorbing interest in the three kingdoms of Nature.

What saith the Scripture?  “Go to the ant thou sluggard.”  In other words, study the Invertebrata.

Ever yours very faithfully,

T.H.  Huxley.

[Sketch of a vast winged ant advancing on a midget, and saying, as it looks through a pair of eyeglasses, “Well, really, what an absurd creature!!”]

4 Marlborough Place, London, April 28, 1878.

My dear Haeckel,

Since the receipt of your letter three months ago, I have been making many inquiries about Medusae for you, but I could hear of none—­and so I have delayed my reply, until I doubt not you have been blaspheming my apparent neglect.